HANOI, Vietnam (AP) — Vietnam released and deported an American pro-democracy activist detained since April, a move that contrasts with the long prison terms given to Vietnamese activists who are members of the same U.S.-based dissident group.

The release of Nguyen Quoc Quan on Wednesday came after U.S. diplomatic pressure and removes an obvious thorn in relations between the former enemies. Both countries are trying to strengthen their ties in large part because of shared concerns over China’s emerging military and economic might, but American concerns over human rights in one-party, authoritarian Vietnam are complicating this.

Vietnam’s Foreign Ministry said in a statement that Quan had “confessed to his crime” and asked for leniency to be reunited with his family. His wife, Huong Mai Ngo, said she doubted this was the case, suggesting that Hanoi was seeking a face-saving way of allowing him to go home.

“I don’t believe it. They say that about everybody,” she said via telephone from Sacramento, Calif. “If my husband was prepared to do that (confess), he could have been released nine months ago.”

Given the diplomatic sensitivities around the case, most observers had expected Quan to be released and quietly deported.

Quan, an American citizen, was arrested at Ho Chi Minh City’s airport in April after arriving on a flight from the United States, where he has lived since fleeing Vietnam by boat as a young man. The 59-year-old is a leading member of Viet Tan, a nonviolent pro-democracy group that Vietnamese authorities have labeled a terrorist organization. He was detained in 2007 in Vietnam for six months, also on charges relating to his pro-democracy activities, before being deported.

Authorities initially accused Quan of terrorism, but he was later charged with subversion against the state, which carries penalties ranging from 12 years in prison to death. Earlier this month, 14 Vietnamese activists associated with Viet Tan were sentenced to up to 13 years in jail.

Ngo said she had yet to speak to her husband, who was on a plane home, but that the U.S. consulate had informed her of his release.

“I can’t believe it,” she said. “I cried over the phone when I was told.”

Asked whether she believed Quan would try to return to Vietnam again, she said: “I can’t stop him, but I hope not.”

In Washington, U.S. State Department spokeswoman Victoria Nuland said it had no higher priority than the safety and security of American citizens abroad. “It’s good news that he’s now been released,” she said.

Quan’s supporters didn’t deny that he had come to Vietnam from his home in California to teach non-violent resistance to the Communist government. His lawyer and family members said earlier this month that his trial on charges of subversion was imminent, but then said it had been postponed for unknown reasons.

According to a copy of the indictment obtained by The Associated Press, Quan met with fellow Vietnamese activists in Thailand and Malaysia between 2009 and 2010 and discussed Internet security and nonviolent resistance. The indictment said he traveled to Vietnam under a passport issued under the name of Richard Nguyen in 2011, when he recruited four other members of Viet Tan.

Vietnam is routinely imprisons proponents of free speech and those who seek to undermine the Communist Party’s monopoly on power. Last year, the country arrested and convicted several bloggers, part of a reaction against Internet-fuelled criticism of corruption, its human rights record and handling of the economy.

U.S. officials said last year they were delaying Washington’s participation in an annual meeting on human-rights concerns because of Vietnam’s lack of progress, including Quan’s arrest. Such consultations have been held every year since 2006. Congress members with large Vietnamese-American constituencies have been putting pressure on the Obama administration to get tough with Vietnam.